public class Example3_6 {
	public static void main (String args[]) {
	   double sum = 0,item = 1;
	   int i = 1,n = 20;
	   while(i<=n) {
	      sum = sum+item;
	      i = i+1;
	      item = item*(1.0/i);
	   }
	   System.out.println("sum="+sum);
	}
}